Known in the present state of the art is a swivelhead welding torch for gas-shielded nonconsumable-electrode arc welding, comprising a body, a swivel head mounted thereon, and current- and gas-supply cables and hoses (cf. USSR Inventor's Certificate No. 230,345, Cl.B23 K 9/16, June 28, 1966).
The torch head is made sectional and is a two-piece construction, each of the sections being swivelling with respect to the other, the plane of jointing making predominantly an angle of 45.degree. with the axis of the torch body.
Since the torch construction fails to provide a simple turning of its head in a single plane, a correction is to be introduced to compensate for a lateral angle of the head inclination which is liable to form every time and is not always desirable, due to swivelling the torch body in an opposite direction with respect to its longitudinal axis. As a result, the torch head rigidly fixed in the body assumes a position inconvenient for the operator, whereby the operator's fatigue is enhanced and labour productivity is reduced. An inconvenient position of the head is augmented due to an unrestricted angle of the head swivel, which is within 90 to 180 degrees with respect to the axis of the torch body.
Furthermore, a close arrangement of the current leads and gas supply hoses to the torch head that is liable to become heated during the welding process, affects adversely the service life of the current leads and gas hoses and of the torch as a whole. The welding torch features comparatively high specific materials consumption and but low maintainability of its construction.
Another prior-art swivel-head welding torch for gas-shielded nonconsumable-electrode arc welding (cf. U.S. Pat. No. 2,986,624, Cl. 219-75, May 30, 1961) is known to comprise a head, two current-supply conduits provided with external electric insulation and held with one of their ends to the torch body and with the other end, connected to the head.
The shielding gas is fed to the torch head along a third conduit which is also held with one of its heads to the torch body, and with the other end, is connected to the head. The junction unit of all the three conduits to the head serves at the same time as the jointing unit of the swivel head which is cooled with water passing along the current-conduction conduits forming a loop soldered to the stationary portion of the unit along the the outside perimeter of the head. Soldered to the same stationary portion of the unit is also the gas-supplying conduit which communicates with an annular gas chamber of the swivel unit, said chamber being isolated from the jointing plane of the swivel unit with a sealing cup of an elastoplastic material, to prevent the gas from escaping therefrom. The head serves at the same time as a movable member of the swivel unit, through which a duct runs which communicates the head interior with the gas chamber of the swivel unit. Both the movable and the stationary members of the swivel unit are locked in place with a screw at a preselected angle of swivel. Such a construction arrangement of the welding torch is too complicated and fails to provide the torch head swivel to an angle exceeding 180.degree., since such a swivel is prevented by the conduits rigidly connected to the stationary member of the swivel unit. Moreover, whenever the angle of the head swivel is to be changed, the screw of the swivel unit has to be undone and retightened, which results in that the head is arranged inconveniently for the operator and in the affected adversely operator's labour productivity. Rigidly fastened gas- and current-supply conduits in the torch body prevent adjustment of the torch as for length and rotation of the torch head with respect to the longitudinal axis of the torch body, which involves difficulties concerned with sophisticated welding techniques, or in some cases imposes much restriction upon the field of application of such a welding torch. In addition, provision of a water cooling system for the torch either renders it inapplicable for operation in the open air at subzero temperatures of the ambient air, or involves material sophistication of the equipment due to the use of a special closed-circuit forced-recirculation cooling system employing anti-freeze solutions as coolants.
Application of a torch without water cooling is not allowed from the standpoint of construction, which restricts substantially the field of the torch application.